320 GASTROPODA. [Pectinibranchia. 



KEY TO SPECIES. 



A. Shell without a basal spiral ridge. 



. Whorls a little separated ; urnbilicated. About 20 axial 



lamellae, interstices smooth . . . . . . tenellum. 



aa. Whorls united ; umbilicus covered. 



b. About 10 axial lamella? on body- whorl . . . . philippinarum . 



bb. About 20 axial lamellse on body-whorl . . . . Jukesianum. 



B. Shell with a basal spiral ridge. 



a. Axial ribs strong, 13-16 on body- whorl ; interstices 



spirally ribbed . . . . . . . . Zelebori. 



aa. Axial riblets numerous, filiform ; body-whorl tricarinate levifoliutuin. 



Sect. 1. EPITONIUM, s. str. 



Shell having the whorls a little separated, crossed by regular 

 lamelliform axial ribs ; urnbilicated. 



1. Epitonium tenellum, Button, 1885. Plate 46, fig. 5. 



Scalaria lineolata, Kiener : Hutton, C.M.M., 22 ; not of Kiener. S. lyra, 

 Sowerby : Hutton, M.N.Z.M., 70 ; not of Sowerby. S. tenella, Hutton, 

 P.L.S. N.S.W., ix, 1885, 943. S. novoseelandica, Clessin, Conch. Cab., 

 Scalariidse, 1897, 57, pi. 15, f. 4 ; Suter, J. Mai., vii, 1899, 54. 



Shell rather small, perforate, thin and fragile, translucent, 

 acuminate, usually with a brown band on the anterior part of the 

 body- whorl. Sculpture consisting of arcuate lamellar axial ribs, most 

 of them discontinuous over the whorls, about 20 on the last whorl ; 

 interstices smooth. Colour light horny, with a narrow brown band 

 below the suture on the last few whorls, continued from the suture and 

 bounding the base on the body-whorl ; a very faintly brown band is 

 sometimes present on the periphery ; riblets white. Spire elevated, 

 conic, about 1J times the height of the aperture ; outlines straight. 

 Protoconch small, sharply conic, of about 3 smooth and convex whorls. 

 Whorls 8 to 9, convex, very little shouldered ; base convex. Suture 

 deep. Aperture slightly oblique, oval. Peristome continuous in adult 

 specimens, thickened by an axial rib, edge blunt, slightly effuse below. 

 Columella short, oblique, slightly arcuate. Inner lip very little ex- 

 panded, with a free and sharp margin, leaving the narrow umbilical 

 perforation open. Operculum unknown. 



Diameter, 5 mm. ; height, 11-5 mm. Angle of spire, 32. 



Animal unknown. 



Type in the Dominion Museum, Wellington. 



Hob. Auckland Harbour ; Bay of Islands. Also Tasmania and 

 Australia. 



Remark. Perfectly white specimens are sometimes found. 



Sect. 2. CLATHRUS, Oken, 1815. 



Clathrus, Oken, " Lehrbuch der Zoologie," 1815. Type: Scalaria communis? 

 Lam. 



Shell moderately thick, often coloured, whorls united ; longitudinal 

 ribs usually numerous, aperture suboval, umbilicus covered by the 

 inner lip, no basal rib. 



